The present invention relates to high speed punching apparatus for cutting parts out of generally flat stock and to a punching tool therefor.
It has been the practice to produce low production sheet metal parts having intricate shapes by means of a band saw. The problem with use of a band saw is the time required to cut the part and the accuracy with which the part can be cut. High speed punching or nibbling, while capable of providing faster results, have had difficulties in tool and die life. Difficulties have been encountered with apparatus accommodating materials of different thickness and hardness and for accommodating a dull tool versus a sharp tool whereby tool stripping is a problem. Difficulties have also been encountered in hang up of burrs on the workpiece in the die button whereby smooth, workpiece feed is inhibited.
The present invention provides apparatus for varying the tool stripping force whereby variation of material thickness and hardness and in the cutting condition of the tool or die can be selectively accommodated. Therefore, it is an object of the present invention to provide apparatus of the above described type having novel means for adjusting to tool stripping force whereby differences in material and tool condition can be accommodated.
The present invention provides a novel stock or workpiece rest for periodically raising the stock away from the die button sufficiently to provide clearance of the formed burrs out of the opening of the die button whereby workpiece feed will not be inhibited. Therefore, it is another object of the present invention to provide apparatus of the above described type including novel stock rest means whereby burr clearance is provided and stock feed is facilitated.
The present invention can be used with a template and has a novel structure assuring that the template will not be cut by the punching tool. Therefore, it is another object of the present invention to provide apparatus of the above described type for use with a template including a novel structure whereby cutting of the template is obviated.
The present invention also provides a novel punching tool structure by which friction with the associated die button is minimized thereby increasing tool life. It is therefore still another object of the present invention to provide a novel punching tool structure in which friction with the associated die button is minimized.
In the present invention the punching tool has a preselected shape whereby the punched workpiece chips will be expelled; therefore it is another object of the present invention to provide a novel punching tool having a preselected shape for assuring that workpiece chips are expelled.